CN101909877A - Method for manufacturing double layer copper clad laminated board, and double layer copper clad laminated board - Google Patents

Abstract

Provided is a method for manufacturing a double layer copper clad laminated board characterized in having improved folding endurance of 150 times or more, as a result of folding endurance test conforming to JIS C6471, by performing heat treatment at a temperature of 100 DEG C or higher but not higher than 175 DEG C to the double layer copper clad laminated board having a copper layer formed on a polyimide film by sputtering and plating. The method is provided for manufacturing the double layer copper clad laminated board (double layer CCL material) wherein the copper layer is formed on the polyimide film by sputtering and plating, folding endurance is improved and breakage of an outer lead section of a circuit is eliminated, and such double layer copper clad laminated board is also provided.

Description

Method for manufacturing double-layer copper-clad laminate and double-layer copper-clad laminate

technical field

The present invention relates to a method for manufacturing a double-layer copper-clad laminate that improves the folding resistance of the laminate in a double-layer copper-clad laminate in which a copper layer is formed on a polyimide film by sputtering and electroplating, and the resulting double layer copper clad laminate.

In addition, the above-mentioned two-layer copper-clad laminate includes a thin intermediate layer in order to increase the bonding strength, and this intermediate layer is called a "two-layer copper-clad laminate" including a polyimide film and a copper layer.

Background technique

In recent years, double-layer copper clad laminates (CCL: Cu Clad Laminate) materials in which a copper layer is formed on a polyimide film have been used as circuit materials for mounting driver ICs such as liquid crystal displays that require fine-pitch circuits. Among the double-layer CCL materials used as COF (chip on film: Chip On Film) laminate materials, especially the double-layer CCL materials produced by sputtering and plating have attracted attention.

The double-layer CCL material is obtained by forming a submicron copper layer on a polyimide film (PI) by sputtering, and then forming a copper layer by copper sulfate electroplating. The basic invention is described in Patent Document 1 below.

Chip On Film (Chip On Film) is used in thin TVs such as LCD TVs and organic EL TVs. The outer leads of the circuit are bent and used, so the bending resistance (folding resistance) must be high.

However, as the finer pitch of the circuit progresses, the width of the circuit becomes narrower, resulting in a problem of lowering the strength. As a result, there is a problem of disconnection of the outer lead portion.

Patent Document 1: US Patent No. 5,685,970

Contents of the invention

In view of the above problems, the purpose of the invention of the present application is to provide in utilizing sputtering and electroplating process to be formed with the double-layer copper-clad laminate (double-layer CCL material) of copper layer on polyimide film, folding resistance improves, can A method of manufacturing a double-layer copper-clad laminate for preventing breakage of an outer lead portion of a circuit, and a double-layer copper-clad laminate obtained thereby.

The inventors of the present invention have carried out extensive and in-depth research in order to solve the above-mentioned problems, and found that when processing a double-layer CCL material with a copper layer on a polyimide film by sputtering and electroplating, by applying certain conditions Under heat treatment, the folding resistance can be significantly improved.

Based on such findings, the present application provides the following inventions.

1) A method for manufacturing a double-layer copper-clad laminate with improved folding resistance, characterized in that the polyimide film is formed on a polyimide film by sputtering and electroplating at a temperature above 100°C and below 175°C. The double-layer copper-clad laminate with the copper layer undergoes heat treatment, and has a folding resistance of more than 150 times measured by a folding resistance test based on JIS C6471.

2) The method for manufacturing a double-layer copper-clad laminate as described in 1) above, wherein a NiCr alloy is formed on the polyimide film by sputtering, and a NiCr alloy is formed between the polyimide film and the copper layer layer.

In addition, this application provides the following inventions.

3) A double-layer copper-clad laminate having a polyimide film and a copper layer formed thereon, characterized in that it has a folding endurance of 150 times or more as measured by a folding endurance test based on JIS C6471.

4) The double-layer copper-clad laminate described in 3) above is characterized in that a NiCr alloy layer is further provided between the polyimide film and the copper layer.

Invention effect

According to the double-layer copper-clad laminate obtained by the present invention, the excellent effects of improving the folding resistance and effectively preventing the outer lead part of the circuit from breaking can be obtained.

Description of drawings

Fig. 1 is an explanatory diagram of a test piece used in a folding test (JIS C6471).

Detailed ways

Regarding the double-layer copper-clad laminate obtained by the present invention, first place it in a vacuum chamber and activate the surface of the polyimide film by plasma treatment, and then attach a single metal layer of 10 to 30 nm of Ni, Co, and Cr by sputtering Or an alloy layer comprising two or more of them, such as a NiCr layer (20% Cr), and then sputtering is used to form a submicron copper layer.

The copper layer thus obtained is called a copper seed layer because it is a seed for the formation of the electrolytic copper layer to be performed later.

Then, electroplating treatment is performed using a copper seed layer. The plating treatment is performed by copper sulfate plating or the like. By adjusting the current density and electrolyte temperature during electroplating, the thickness of the coating can be adjusted arbitrarily. Thus, a double-layer copper-clad laminate of a polyimide film and a copper layer can be obtained. For the plating treatment, a plating solution previously developed by the present applicant can be used (refer to WO2006/080148). The surface roughness of the plating layer was measured using a non-contact surface roughness meter (manufactured by Veeco). As a result, Ra was 0.01-0.04, Rt was 0.14-1.0, and Rz was 0.1-0.90.

Before forming a submicron copper layer by sputtering, a connection layer (Tie Coat) containing NiCr can be formed on the surface of the polyimide film by sputtering. Plasma treatment of polyimide film surface and tie layer are effective means in improving adhesion. The invention of this application includes these processes.

As mentioned above, the present invention includes forming a thin intermediate layer, that is, a connection layer containing NiCr in order to increase the bonding strength, together with this intermediate layer called "double-layer copper-clad laminate" of polyimide film and copper layer .

The polyimide film used for the double-layer CCL material of the present invention is not particularly limited as long as the present invention can be realized, but a BPDA-PPD-based polyimide film is preferably used.

A two-layer copper-clad laminate obtained by forming a copper layer on a polyimide film by sputtering and plating is heat-treated at a temperature of 100° C. or higher and 175° C. or lower. Accordingly, it is possible to have a folding endurance of 150 times or more measured by a folding endurance test based on JIS C6471.

If the heat treatment conditions are lower than 100° C. or higher than 175° C., none of them will have a folding resistance of 150 times or more. Therefore, heat treatment needs to be performed at a temperature of 100°C or higher and 175°C or lower.

The test conditions of the folding test based on JIS C6471 are as follows.

Using a folding resistance test piece with R=0.38, load 500gf, bending angle: 135°±5°, 175cpm (175 bending times per minute), and L/S of 1mm, the number of times until breaking was defined as Folding resistance.

When producing a test piece, a dry film was crimped on the heat-treated two-layer copper-clad laminate, exposed to light to form a pattern, and an etching process was performed to remove unnecessary portions of copper. And, finally, the dry film is removed, and a circuit is formed on the polyimide film. The test piece produced in this way was used.

This circuit forming method is a method generally performed, and other methods may also be performed. The etchant of the copper layer generally uses an etchant of the following liquid composition.

(liquid composition)

Copper Chloride Solution (CuCl ₂ ), Copper Oxide (CuO)

Hydrochloric acid (HCl): 3.50mol/L (adjust within the range of 0-6mol/L)

Hydrogen peroxide (H ₂ O ₂ ): 30.0Cap (adjust within the range of 0-99.9Cap)

Example

Hereinafter, the characteristic of this invention is demonstrated concretely based on an Example and a comparative example. In addition, the following description is for easy understanding of the present invention, and the present invention is not limited thereto. That is, the invention of this application also includes modifications, embodiments, and other examples based on the technical idea of the invention of this application.

(Example 1)

Using a polyimide film with a thickness of 34 μm (Ube Industries, Ltd., UpilexSGA), a NiCr layer (20% Cr) of 25 nm was deposited by sputtering, and then a copper layer with a thickness of 8 μm was formed by sputtering and plating. The double-layer copper-clad laminate was heat-treated at 100° C. for 2 hours using a vacuum heat-treatment furnace.

A dry film was laminated on the heat-treated double-layer copper-clad laminate, and patterned by exposure. Unnecessary parts of copper were removed by etching using the above-mentioned etching solution to form a circuit with L/S=1 mm.

Then, the dry film was finally removed to prepare a test piece with a size of 15 mm×130 mm. The circuit on the polyimide film is composed of a continuous one, which is folded back along the length direction of the polyimide film to form a structure of six parallel circuits. An explanatory diagram of the test piece is shown in FIG. 1 .

Using this test piece, a folding test based on JIS C6471 was performed. A testing machine manufactured by Testa Industrial Co., Ltd. was used. The test was carried out under the conditions of R=0.38, load 500gf, bending angle: 135 degrees, and 175 cpm (bending at a ratio of 175 times per minute). The results are shown in Table 1 including Examples and Comparative Examples described later.

As shown in Table 1, the folding endurance (MIT) until breaking was 154 times. This example has a folding endurance of 150 times or more in the invention of the present application.

Table 1

Example Comparative Example Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Heat treatment temperature (℃) 100 125 150 175 - 75 200 Folding resistance (MIT) 154 178 161 150 124 136 138

Folding resistance: MIT (number of bends until fracture), -: no heat treatment

(Example 2)

The double-layer copper-clad laminate used in Example 1 above was heat-treated at 125° C. for 2 hours using a vacuum heat-treatment furnace.

In the same manner as in Example 1, a dry film was laminated on the heat-treated double-layer copper-clad laminate, and then exposed to form a pattern, and an etching treatment was performed to remove unnecessary parts of copper to form a circuit with a width of 1 mm.

Then, a folding test based on JIS C6471 was performed in the same manner as in Example 1. As shown in Table 1, the folding endurance (MIT) until breaking was 178 times. This example has a folding endurance of 150 times or more in the invention of the present application. In addition, folding endurance (MIT) was further improved compared with Example 1.

(Example 3)

The double-layer copper-clad laminate used in Example 1 above was heat-treated at 150° C. for 2 hours using a vacuum heat treatment furnace.

In the same manner as in Example 1, a dry film was laminated on the heat-treated two-layer copper-clad laminate, exposed to light, patterned, and etched to remove unnecessary copper to form a circuit with a width of 1 mm.

Then, a folding test based on JIS C6471 was performed in the same manner as in Example 1. As shown in Table 1, the folding endurance (MIT) until breaking was 161 times. This example has a folding endurance of 150 times or more in the invention of the present application. In addition, folding endurance (MIT) was further improved compared with Example 1.

(Example 4)

The double-layer copper-clad laminate used in Example 1 above was heat-treated at 175° C. for 2 hours using a vacuum heat treatment furnace.

In the same manner as in Example 1, a dry film was laminated on the heat-treated two-layer copper-clad laminate, exposed to light, patterned, and etched to remove unnecessary copper to form a circuit with a width of 1 mm.

Then, a folding test based on JIS C6471 was performed in the same manner as in Example 1. As shown in Table 1, the folding endurance (MIT) until breaking was 150 times. This example has the folding endurance of 150 times or more of the invention of the present application, but the folding endurance (MIT) is lower than that of Examples 2 and 3.

As can be seen from the above examples, heat treatment at 100 to 175° C. improves the folding resistance, but it can be seen that the folding resistance is hardly improved near the lower limit or near the upper limit.

Therefore, the conditions of Example 2 and Example 3 can be said to be more suitable conditions. In the examples, the heat treatment was performed for 2 hours, but since the heat treatment itself is performed at a relatively low temperature, even if the heat treatment time is longer than 2 hours, the folding resistance hardly changes. Long-time heat treatment is a cause of poor productivity, so it can be said that it is desirable to perform it within a range of about 1 hour to about 5 hours.

(comparative example 1)

The two-layer copper-clad laminate used in Example 1 above was used as a test piece without heat treatment. In the same manner as in Example 1, a dry film was laminated on this two-layer copper-clad laminate, exposed to light to form a pattern, and an etching process was performed to remove unnecessary portions of copper to form a circuit with a width of 1 mm.

Then, a folding test based on JIS C6471 was performed in the same manner as in Example 1. As shown in Table 1, the folding endurance (MIT) until breaking was 124 times. This example does not have the folding endurance of 150 times or more in the invention of the present application at all. This example is a conventional double-layer copper-clad laminate, which cannot cope with the problem of narrowing the circuit width and reducing the strength due to the fine pitch of the circuit, and it is easy to predict the occurrence of a failure of the outer lead part to be disconnected.

(comparative example 2)

The double-layer copper-clad laminate used in Example 1 above was heat-treated at 75° C. for 2 hours using a vacuum heat treatment furnace.

In the same manner as in Example 1, a dry film was laminated on the heat-treated two-layer copper-clad laminate, exposed to light, patterned, and etched to remove unnecessary copper to form a circuit with a width of 1 mm.

Then, a folding test based on JIS C6471 was performed in the same manner as in Example 1. As shown in Table 1, the folding endurance (MIT) until breaking was 136 times. This example does not have the folding endurance of 150 times or more of the invention of the present application. Therefore, it was confirmed that the heat treatment temperature was insufficient.

(comparative example 3)

The double-layer copper-clad laminate used in Example 1 above was heat-treated at 200° C. for 2 hours using a vacuum heat treatment furnace.

In the same manner as in Example 1, a dry film was laminated on the heat-treated two-layer copper-clad laminate, exposed to light, patterned, and etched to remove unnecessary copper to form a circuit with a width of 1 mm.

Then, a folding test based on JIS C6471 was performed in the same manner as in Example 1. As shown in Table 1, the folding endurance (MIT) until breaking was 138 times. This example does not have the folding endurance of 150 times or more of the invention of the present application. Therefore, it can be seen that the folding resistance deteriorates even if the heat treatment temperature is too high.

Industrial applicability

According to the double-layer copper-clad laminate obtained by the present invention, the excellent effect of improving the folding resistance and effectively preventing the breakage of the outer lead part of the circuit can be obtained, so it is most suitable as a driver IC mounting circuit such as a liquid crystal display that requires a fine-pitch circuit. Material.

Claims (4)

1. A method for manufacturing a double-layer copper-clad laminate with improved folding resistance, characterized in that, Double-layer copper cladding in which a copper layer with a surface roughness (Rz) of 0.1 μm to 0.9 μm is formed on a polyimide film by sputtering and electroplating at a temperature of 100° C. to 175° C. The laminated board is heat-treated, and has a folding resistance of 150 times or more measured by a folding resistance test based on JIS C6471. 2. The manufacturing method of double-layer copper-clad laminated board as claimed in claim 1, wherein, Form a single metal layer of Ni, Co or Cr or an alloy layer containing two or more of them on the polyimide film by sputtering, and then use sputtering and electroplating to form a surface roughness (Rz) of 0.1 μm or more and Copper layer below 0.9μm. 3. A double-layer copper-clad laminate having a polyimide film and a copper layer formed thereon, characterized in that, The surface roughness (Rz) of the copper layer is not less than 0.1 μm and not more than 0.9 μm, and has a folding endurance of 150 times or more measured by a folding endurance test based on JIS C6471. 4. The double-layer copper-clad laminate according to claim 3, wherein: There is also a single metal layer of Ni, Co or Cr or an alloy layer containing two or more of them between the polyimide film and the copper layer.

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